Cheap way to combine two red beams?

[kiyoukan]

i think i might try the old way, diffraction grating.
i can combine many beams.

 

[ReNNo]

Can you explain that method?

 

[kiyoukan]

its simple if you shine a laser into a diffraction grating and record the exact angle they come out you can also do the reverse, shine laser in the same way they came out and it will align them.
This is a bit of an over simplification there was a thread on it along time ago with pics but i cant locate it.

 

[HIMNL9]

@Kyoukan: sorry, but this can work only in theory ..... diffraction gratings works in both the ways, are not unidirectional devices ..... you can shine two beams on the same point, with the correct angles, but the diffraction grating just diffract both the beams in multiple ones, don't give you a single beam from 2 (it was too easy, otherwise )

 

[Grix]

Why does almost every dual red setup I've seen use two parallell diodes, a mirror and a PBS?
Isn't it much simpler to use two diodes in 90 degree angle to each other with the PBS cube directly in the middle? (No need for a mirror to complicate things)

 

[ReNNo]

Maybe people don't want to use two heatsinks instead of only one.

 

[HIMNL9]

Why does almost every dual red setup I've seen use two parallell diodes, a mirror and a PBS?
Isn't it much simpler to use two diodes in 90 degree angle to each other with the PBS cube directly in the middle? (No need for a mirror to complicate things)

Uhm ..... are you asking just casually, or have you looked in my "big-box-of-never-finished-projects" ?

(anyway, this was just an idea, for couple 2 LOCs with a PBS before the lens ..... it works, but they are just pressed in the holes, til now, not yet finished with thermal glue and heat exchanger pieces, and also i need a "taper/threader" 9x1 for make the hole for the lens holder in the aluminium plate, that i don't have, for finish it ..... and, doing all with handy tools, i was unable to made it smaller, probably with machines, someone can build something better and smaller )

 

[jaycey]

Dont the LOC's have to be electrically insulated from each other?

 

[HIMNL9]

I was using them in parallel, with decoupling resistors (not the better way, i admit, but there was no way for made it so small, keep a thermal exchange, and insulate them at the same time)

 

[jaycey]

I dont fully understand (must google "decoupling resistors")

Good thinking though, thanks.

 

[HIMNL9]

I dont fully understand (must google "decoupling resistors")

Good thinking though, thanks.

Sorry ..... "decoupling resistors" are simply resistors placed in series to each diode for balance them ..... cannot balance correctly two paralleled diodes, if connected directly, cause a minimal difference in one of them, can draw all the current and blow it ..... like leds ..... so, placing identical resistors (15 / 20 ohm) in serie to each LDs, helps to prevent this, "decoupling" them one from the other.

Is like when you need to parallel power transistors ..... never do it without use low values decoupling resistors .....

 

[ReNNo]

Uhm ..... are you asking just casually, or have you looked in my "big-box-of-never-finished-projects" ?

(anyway, this was just an idea, for couple 2 LOCs with a PBS before the lens ..... it works, but they are just pressed in the holes, til now, not yet finished with thermal glue and heat exchanger pieces, and also i need a "taper/threader" 9x1 for make the hole for the lens holder in the aluminium plate, that i don't have, for finish it ..... and, doing all with handy tools, i was unable to made it smaller, probably with machines, someone can build something better and smaller )

Nice, but how difficult will be to adjust length from diode to lens.
For that purpose you need special made holder with screws for fine adjustment. (So you can move one diode forward/backward but very precisely) I don't know how achievable is that in practice..

 

[HIMNL9]

Nice, but how difficult will be to adjust length from diode to lens.
For that purpose you need special made holder with screws for fine adjustment. (So you can move one diode forward/backward but very precisely) I don't know how achievable is that in practice..

I solved this particular problem placing the end of the diodes "in contact" with the cube (so the light path is the same lenght) ..... the real difficult is to align them, cause the diodes are just pressed in the frame .....

Anyway, this particular setup was simply an experiment for see if i can made something for couple 2 LOCs small enough for be placed in a handheld ..... too difficult to build it for any production level, and also i stopped the experiment, for now ..... i keep it, cause maybe one day i have the time for finish it.

Also, not all the cubes from sleds works with red LDs ..... i discovered, as example, that the original PBS from PHR sleds don't work with red, where instead old PBS cubes from cd/dvd readers or burners works .....

And yes, must place the lens at 1mm or less from the cube, for focus them ..... the PBS cube elongate the path, but not too much ..... probably a better setup can be built usinf two small lenses "glued" in front of the diodes, for pre-focusing, and a single focusing element after the cube for final focusing, but i don't have machines for build the needed frame, and also, probably cannot be done so small .....

 

[Benm]

Thats all fine though.. you can operate these diodes in paralel if you provide a 1 ohm or so series resistor for each one on the hot end. Its not rocket science to get that to work - just dont just bluntly connect the in paralel and expect identcal Vf values.

 

[Bionic-Badger]

Well this 50/50 beam splitter definitely splits the beam nicely, but it is not polarized, so no summation, unless you want two beams. Still, it's a nice piece of optics.

 

[ReNNo]

Cube has just arrived this morning.



It splits any beam very nicely and build quality is great.
But it cannot combine two beams.

Ahhh, my low budget laser scanner becomes more and more expensive.